1. Field of the Invention
The present invention relates generally to systems and methods for laser processing/manipulation, such as laser ablation, and particularly to systems and methods for small scale processes, such as semiconductor inspection, device editing, microsystem modification, sample preparation and MEMS manufacturing using laser.
2. Description of the Prior Art
Laser has been used to manipulate materials in a variety of ways. This includes laser ablation (material removal or a subtraction process), laser deposition (an additive process), laser machining, laser milling, and laser inspection (often combined with laser cutting). Laser is increasingly substituting or supplementing focused ion beam (FIB) milling, and replacing diamond saws in applications such as TEM sample preparation for semiconductor devices.
The phenomenon of laser ablation of a material has been known and studied for years, but the results with older nanosecond-regime laser technologies operating at one billionth of a second (10−9 sec) would not have sufficed for the small structures of current and near-future silicon-based integrated-circuit technologies and other types of microstructures such as nanotechnology. Lasers operating in the sub-picosecond regime (SPR) have been applied to the ablation of a material, such as silicon. More recently, laser of even shorter pulses, namely femtosecond laser, has started to have applications. These latest lasers promise superior performance and ease of application. In particular, ultrashort laser pulses such as femtosecond laser pulses promise to overcome a very common thermal damage problem associated with older lasers. Typical laser machining using relatively longer pulses tends to leave thermal damage on the micrometer scale. For devices having a size scale near or under micrometers, thermal damage is generally unacceptable. Femtosecond laser promises to eliminate such thermal damages caused during laser ablation. In addition, ultrashort pulsed lasers have also demonstrated potential for fabricating sub-micron features in diverse substrates by taking advantage of the sharp boundaries of optical breakdown created by femtosecond pulses of laser light.
Given the importance of laser manipulation of materials, it is desirable to develop a new laser manipulation system that is faster, more flexible and more accurate.